1. Field of the Invention
The present invention relates, generally, to a device for separating the utlimate sheet from a stack thereof. More particularly, the device of the present invention relates to one designed to remove the ultimate sheet from a stack of flexible sheets by use of a vertically displaceable separating element located along one transverse edge of the stack, and connected with pivotal levers disposed along opposing longitudinal edges of the stack.
2. Description of the Prior Art
Various devices of the type characterized herein are known in the art for separating the ultimate sheet from the sheets lying therebeneath in the form of a stack. One such apparatus is disclosed in German Offenlegungsschrift No. 2,007,594, which is comprised of separating elements arranged opposite each other to contact the front corners of the stack. Drive rollers are caused to contact the ultimate sheet and advance the same against the restraining force of these separating elements, thus causing the ultimate sheet to arch and bend at the corners until the inherent elasticity of the sheet results in the leading edge thereof resiliently snapping over the lips of the corner separating elements, whereby that sheet is separated from the stack.
The corner separating elements of this disclosed apparatus are mounted on swivel arms which extend along the outer surface of guide bars and execute a generally vertical movement along an arched path. In order to align the front end of the stack to correspond with the arched path along which the separating elements move downwardly, a front stop is provided which is capable of being moved into a vertical position, or from the vertical position into contact with the stack. This stop is employed with a stop unit which is arranged between the separating elements and which is firmly connected, at the lower end, to a shaft mounted for rotation in jaws below the surface of the stacking tray. In a vertical position, the stop unit is disposed behind, and at a slight distance from, the forward section of the separating element to compensate for the arched path thereof. When a stack of sheets is placed in the tray so that the stack contacts the front end of the stop unit, the lower sheets in the stack are arranged behind the downwardly directed sections of the separating element, thus enabling the same to move downwardly along the arched path without interference by these lower sheets in the stack.
The device of this disclosed invention is quite expensive because, in addition to the arms employed to swivel the separating elements, a separate stopping device is provided which must be rotatable about a shaft in order to appropriately account for the arched, downwardly extending path of the separating element. This complex configuration is necessary to render possible the separation of the lowermost sheets of the stack without difficulty.
Another device, similar to the one described above and useful for separating sheets from a stack thereof, is disclosed in German Offenlegungsschrift No. 2,265,108, and comprises control means which cause the corner separating elements to be in substantially constant contact with the corner of the stack during the separating or dispensing process, and to move along a vertically downward path during that operation. To effectuate this operation, a lever is attached to a side plate provided with curved slots or channels which receive pegs protruding from the lever. These elongated curved slots are specifically shaped such that the pegs will follow the contour thereof as the lever is moved, whereby the sheet separating element moves vertically downward. A cam system is provided for lifting the lever along the path, the same being predetermined by the movement of the pegs in the slots or channels. This device also is characterized as comprised of relatively expensive elements, necessary in order to move the corner separating elements along an approximately vertical path.
Accordingly, the need exists to provide a sheet dispensing device which is capable of simple and efficient separation of the ultimate sheet from a stack thereof, and one which, most especially, is of simple design and economical construction.